#!/bin/bash

# Copyright 2023 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# https://stackoverflow.com/questions/50413579/bash-convert-netmask-in-cidr-notation
c=0 x=0$(printf '%o' ${1//./ })
while [ $x -gt 0 ]; do
  let c+=$((x % 2)) 'x>>=1'
done
echo $c
